Measurements and Analysis of the Liquid Viscosity and Liquid Density of Five Phenyl Propanol Isomers

Liquid viscosity and density are important properties in scientific and industrial applications. This study measures the pure component viscosities and densities of five phenyl propanol isomers used as fragrance or flavor enhancers: 1-phenyl-1-propanol (1P1P), 1-phenyl-2-propanol (1P2P), 2-phenyl-1-propanol (2P1P), 2-phenyl-2-propanol (2P2P), and 3-phenyl-1-propanol (3P1P). Prior to this work, little or no experimental data existed for these properties in the literature. Viscosities were measured using an Ubbelohde capillary viscometer from SI Analytics at temperatures from 293.15 to 333.15 K. The densities were measured using an Anton Paar DMA 5000 Density Meter at temperatures from 293.15 to 333.15 K. Both properties were measured at ambient pressure (84–87 kPa) in Provo, UT. Results show that liquid viscosity is dependent on the position of the alcohol group relative to the phenyl group as the different configurations affect the ability of each chemical to hydrogen bond with neighboring molecules. Density is also affected by the proximity of the alcohol group to the phenyl group, but appears to be more dependent on molecular packing rather than hydrogen bonding. A discussion of the impact of these structural effects on both viscosity and density is presented, and the performance of existing estimation methods is evaluated.